Operating System
OS Part-1
OS Part-2
- File Concepts and Access methods
- Free Space Management and Allocation methods
- Directory Systems and Protection
- File Organization, Sharing and Implementation issues
- Disk and Drum Scheduling
- I/O Devices Organisation & I/O Buffering
- I/O Hardware, Kernel I/O subsystem and Transforming I/O Requests to Hardware Operations
- Device Drivers and Path Management
- Device Driver Sub Modules and Procedure
- Device Scheduler and Handler
- Interrupt Service Routine (ISR)
- File System in Linux and Windows
OS Part-3
- Process and Process Control Block(PCB)
- Process Scheduling( Preemptive and Non Preemptive)
- Scheduling Algorithms
- Algorithm Evaluation
- Multiple Processor Scheduling
- Real Time Scheduling
- Operations on Processes
- Threads
- Inter-Process Communication
- Precedence Graphs
- Critical Section Problem
- Semaphores
- Classical Problems of Synchronization
- DeadLock
- Deadlock Prevention and Avoidance
- Deadlock Detection and Recovery
- Process Management in Linux
OS Part-4
- Memory Hierarchy in OS
- Concepts of Memory Management
- MFT and MVT
- Logical and Physical Address Space
- Swapping
- Contiguous and Non Contiguous Memory Allocation
- Paging
- Segmentation
- Paging Combined with Segmentation
- Structure and Implementation of Page Table
- Virtual Memory in OS
- Cache Memory Organization
- Demand Paging
- Page Replacement Algorithms
- Allocation of Frames and Thrashing
- Demand Segmentation
OS Part-5
- Distributed Operating System: Introduction and Types
- Distributed OS: Design Issues
- Distributed OS: File System
- Distributed OS: Remote File Access
- Remote Procedure Call(RPC)
- Remote Method Invocation(RMI)
- Distributed Shared Memory
- Parallel Processing and Concurrent Programming
- Security and Threats Protection in Distributed OS
- Security Design Principles and Authentication in Distributed OS
- Sensor Network and Parallel OS
1. Operating System Services
Operating System services ka kaam users aur programs ke liye hardware aur software manage karna hota hai.
OS ke Main Services:
1. Process Management
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Kya karta hai?
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Naye processes create, schedule aur terminate karta hai.
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CPU time ko processes ke beech allocate karta hai.
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Example:
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Agar tum browser, music player, aur VS Code ek saath use kar rahe ho, toh OS multi-tasking handle karta hai.
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Diagram:
[User ne program open kiya] → [OS ne process banaya] → [CPU process ko execute karega]
2. Memory Management
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Kya karta hai?
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Har program ko memory allocate aur free karta hai.
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Jab RAM full hoti hai toh Virtual Memory ka use karta hai.
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Example:
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Agar tumne bohot saari Chrome tabs open kar li, toh OS memory efficiently assign karega.
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Diagram:
[Process ne memory maangi] → [OS ne memory allocate ki] → [Process use karega]
3. File Management
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Kya karta hai?
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Files ko create, read, write aur delete karta hai.
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File permissions control karta hai.
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Example:
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Agar tum MS Word me ek document save kar rahe ho, toh OS usko manage karega.
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Diagram:
[User ne file save ki] → [OS ne file ko system me store kiya]
4. Device Management
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Kya karta hai?
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Input/output devices ko detect aur control karta hai.
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Device drivers ka use karta hai taaki hardware properly work kare.
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Example:
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Agar tum USB pen drive connect karte ho, toh OS usko detect karega.
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Diagram:
[USB plug-in] → [OS ne driver load kiya] → [Device ready to use]
5. Security & Protection
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Kya karta hai?
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Unauthorized access se data aur system ko protect karta hai.
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Password protection, firewall, encryption provide karta hai.
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Example:
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Jab tum Windows ya mobile me password ya fingerprint lagate ho.
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Diagram:
[User ne login kiya] → [OS ne verify kiya] → [Access allowed]
6. User Interface (UI) Services
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Kya karta hai?
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Users ko CLI (Command Line Interface) ya GUI (Graphical User Interface) provide karta hai.
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Example:
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Linux me Terminal (CLI) aur Windows me Explorer (GUI) hota hai.
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7. I/O System Management
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Kya karta hai?
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Keyboard, mouse, printer jaise input/output devices manage karta hai.
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Example:
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Tumne MS Word se print command diya, toh OS print handle karega.
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8. Networking Services
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Kya karta hai?
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Internet aur Wi-Fi, LAN, Bluetooth connections manage karta hai.
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Example:
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Agar tum files share kar rahe ho Wi-Fi se.
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2. Operating System Structure
Operating Systems different structures me design hote hain taaki efficiency aur security badh sake.
OS ke Main Structures:
1. Monolithic Structure
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Kya hota hai?
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Saare OS services (Process, Memory, I/O, Files) ek hi kernel me combined hote hain.
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Advantages:
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Fast execution hota hai.
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Disadvantages:
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Modify karna mushkil hota hai.
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Example OS:
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MS-DOS, Purane UNIX versions
Diagram:
[Kernel (Single Unit)] → [File, Process, Memory, Device Management]
2. Layered Structure
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Kya hota hai?
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OS multiple layers me divide hota hai, har ek layer ka apna specific kaam hota hai.
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Advantages:
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Debugging aur updating easy hota hai.
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Disadvantages:
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Performance slow ho sakta hai kyunki har layer ek dusre se communicate karti hai.
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Example OS:
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Windows NT, THE OS
Diagram:
3. Microkernel Structure
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Kya hota hai?
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Sirf basic OS functions (CPU scheduling, memory management) kernel me hote hain, baaki sab user mode me execute hote hain.
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Advantages:
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Security aur stability zyada hoti hai.
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Disadvantages:
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Performance slow ho sakti hai context switching ki wajah se.
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Example OS:
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MacOS, QNX, MINIX
4. Modular Structure
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Kya hota hai?
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OS me modules load hote hain, jisme har service ek alag module hota hai.
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Advantages:
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Easily extendable (drivers bina reboot ke install ho sakte hain).
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Disadvantages:
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Agar ek module crash ho jaye toh system unstable ho sakta hai.
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Example OS:
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Modern Linux, Windows NT
Diagram:
[Kernel]→[Modules (File, Device, Network)]
5. Hybrid Structure (Mixed Structure: Monolithic + Microkernel)
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Kya hota hai?
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Monolithic aur Microkernel ka combination hota hai taaki speed aur security dono achi ho.
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Advantages:
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Fast, secure, aur modular design.
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Disadvantages:
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Development complex hota hai.
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Example OS:
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Windows 10, Linux, macOS
Diagram:
[ Hybrid Kernel ] → [ Mix of OS Services in Kernel & User Mode ]
Conclusion
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OS Services user aur hardware ke beech bridge ka kaam karte hain.
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OS Structure performance, security, aur modularity ko affect karta hai.
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Modern OS (Windows, Linux, macOS) Hybrid ya Modular structure use karte hain.